1. The Field of the Invention
The present invention relates to a hypodermic needle system and a method to reduce the incidence of infections caused when injecting fluids into a human or animal. More particularly, the present invention relates to a hypodermic needle with a removable insert disposed in the hollow channel of the needle which may protect the channel from becoming contaminated prior to delivery of a pharmaceutical compound or other therapeutic agent to a patient.
2. State of the Art
There are many methods for administering a compound to achieve a therapeutic effect in humans or animals known in the art, such as ingestion, inhalation, injection, and transmucosal administration. There are, however, advantages and disadvantages with each of these methods of administration. For example, ingestion may be the simplest way to administer a pharmaceutical compound or other therapeutic agent, e.g. a drug, and may be preferred by patients over other methods, but a drug that is ingested will be subjected to the low pH of the gastric juices and the first-pass effect of the liver. Thus, drugs that are ingested are often administered at relatively high doses which can cause unwanted side effects. Additionally, the site of action for a drug can limit whether they can be administered orally, such as when a biological barrier would have to be crossed.
The disadvantages of administering a drug through ingestion can be overcome by injecting the drug directly at its site of action, but administering the drug by injection increases the chance of infection in the patient. Although infection due to injections can often be minimized by using proper aseptic technique, there are a variety of procedures in which a needle must be inserted into the body through a tissue which cannot be readily sterilized. However, because other methods of administering the drug may be less effective or not effective at all, it may be required to inject the drug anyway to effectively treat a particular disease or condition. This is often the case, for example, when treating eye diseases or conditions because the blood-ocular barrier keeps most drugs out of the eye.
Under normal circumstances, the blood-ocular barrier protects a human or animal by providing natural resistance against organisms invading the vitreous humor, the clear gel that fills the space between the lens and the retina of the eyeball. The immune response of a human or animal to an organism that is introduced into the vitreous humor is more limited than if the organism was present in other areas of the body. Thus, a medical procedure that disrupts the integrity of the globe of the eye, such as intravitreal injections to treat a disease or condition of the eye, can lead to infection and inflammation of the eye, i.e. endophthalmitis. It has been found that when the needle passes through the exterior membranes surrounding the eyeball (the conjunctiva), bacteria, which are present normally, can be introduced into the interior hollow channel of the needle and ultimately deposited in the vitreous humor when a substance is injected.
Moreover, because the conjunctiva cannot be readily sterilized prior to intravitreal injections the risk of infection is not as minimal as is desired with such injections. Some, common complications of endophthalmitis are decreased vision and/or permanent vision loss. Some patients may even require enucleation to eradicate a blind and painful eye.
Intravitreal injection of various drugs has become a mainstay of treatment in ophthalmology. It is currently estimated that approximately 1000 to 3000 infections due to intravitreal injection occur each year with approximately half of those infections resulting in legal blindness. The number of injections given each year is increasing as the understanding of how to treat certain eye diseases or conditions increases, and/or new drugs for treating such diseases or conditions become available. For example intravitreal injections may be given to treat viral retinitis, age-related macular degeneration, cystoid macular edema, diabetic retinopathy, uveitis, vascular occlusions, and even endophthalmitis.
Thus, there is a need for a hypodermic needle system and method that substantially minimizes infections caused by injections of fluids in humans and animals. It is desirable that such a hypodermic needle system is relatively easy to use. It is also desirable to provide such a hypodermic needle system which is inexpensive and easy to manufacture.